The present invention relates to a vehicle brake system of a motor vehicle.
In particular, the present invention relates to a vehicle brake system of a motor vehicle with an electronically controllable brake booster comprising a vacuum chamber and a pressure chamber which are separated from each other by a movable wall, a control valve arrangement which can be actuated by means of an electromagnetic actuation means and by means of which a pressure difference between the pressure chamber and the vacuum chamber is adjustable, with the movable wall changing its position as a function of the pressure conditions in the vacuum chamber and in the pressure chamber, thereby actuating a master cylinder, with the electromagnetic actuation means being supplied with current signals by an electronic control unit during operation, which the electronic control unit generates as a function of driving dynamics conditions or external influences.
Such a vehicle brake system is known, for example, from DE 43 24 205 A1.
Such vehicles brake systems are employed for motor vehicles which are equipped with vehicle-to-vehicle ranging controls and cruise controls, or with combinations of these two controls (AbstandsRegelTempomaten--automatic ranging/cruise controls). One of the problems of these systems, however, is that these controls are relatively unreliable, because for a rapid control there exists too much play, backlash, or tolerance-related free travel in the vehicle brake system.
The consequence of this is that braking distance is "given away". At a vehicle speed of 200 km/h and a vehicle brake system-related lost time of only 200 ms, this "given away" braking distance amounts to 11 m! Compared to a braking distance of approx. 193 m (at a deceleration of 8 m/s.sup.2) this corresponds to approx. 6%. Moreover, the control can exhibit an unsuitable transient behaviour or an overshooting behaviour as well.